JPH08102562A - Hall element - Google Patents

Abstract

PURPOSE: To provide a highly sensitive heterojunction Hall element having a low temperature coefficient. CONSTITUTION: A Hall element is formed of heterojunction, which provides a band gap difference of 0.6eV or more, such as of GaInAs and Al InP. Thus, it has high sensitivity and a temperature coefficient 0.1%/ deg.C or less, which is equivalent to that of the conventional GaAs Hall element.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Hall element, and more particularly to a heterojunction Hall element composed of a semiconductor heterojunction which provides high sensitivity characteristics.

[0002]

2. Description of the Related Art A Hall element is a kind of magnetic sensor and is used as a rotation sensor, a current sensor or the like. Recently, a heterojunction Hall element utilizing the high electron mobility characteristics developed by a semiconductor heterojunction has been developed to meet the demand for higher sensitivity of the Hall element. G
a Hall element consisting of a heterojunction of _0.47 In _0.53 As and InP is also an example (Obuyama Shinobu et al., Proceedings No. 3, 10 of the 53rd Annual Meeting of the Japan Society of Applied Physics, Autumn 1992).
78, Lecture No. 16a-SZC-16).

Heterojunctions between Ga _0.47 In _0.53 As and InP _exhibit high electron mobility (Kenjiro Konuma et al., 19
1992 Autumn 53rd Annual Meeting of the Japan Society of Applied Physics Proceedings No.
1, pp. 182, Lecture No. 18a-ZE-3), high sensitivity of Hall elements has been achieved. Like the sensitivity, the small temperature coefficient α of the Hall output voltage is also an important characteristic of the Hall element. The temperature coefficient α is usually the rate of change of the Hall output voltage with temperature, which is obtained by the following equation (1). α (%) = {(V _T2 −V _T1 ) / V _T1 } / (T ₂ −T ₁ ) ... Formula (1) where V _T1 and V _T2 are Hall output voltages at temperatures T ₁ and T _2. Is. In the Ga _0.47 In _0.53 As / InP heterojunction Hall element, α is 0.1 to 0.2% / ° C. (Okuyama Shinobu et al., Proceedings of the 53rd Autumn Meeting of the Applied Physics Society of Japan, 1992). 3, p. 1078, lecture number 16a-
SZC-16). This is larger than 0.05% / ° C of a general GaAs Hall element. In order to form a high performance Hall element, it is necessary to have high sensitivity, that is, a large Hall voltage output and a small temperature coefficient.

Α depends on the band gap (band gap) of the semiconductor material forming the magnetosensitive layer. The magnetic sensing layer refers to a semiconductor layer that has a function of detecting a magnetic field and generating a Hall voltage. When the magnetic sensitive layer is composed of a single semiconductor layer,
α tends to increase as the band gap of the semiconductor forming the magnetosensitive layer decreases. For example, the band gap of InSb at room temperature is 0.17 eV, and α is as large as about 2% / ° C. corresponding to the low band gap. On the other hand, α is about 0.05% for GaAs with a bandgap of 1.43 eV.
/ ° C decreases.

In the case of a magneto-sensitive layer including a heterojunction, α tends to depend on a difference in band gap between semiconductor layers forming the heterojunction. Conventional Ga _0.47 In _0.53 As / InP
Taking a heterojunction system as an example, the band gap of Ga _0.47 In _0.53 As at room temperature is 0.86 eV (HC Case
y, Jr., and MB Panish, `` HETEROSTRUCTUR LASERS-P
art B ”(Academic Press (1978), p. 16). The band gap of InP is 1.34 eV, so the difference in bandgap is 0.
It will be 48 eV. Further, α of the heterojunction Hall element composed of Ga _0.47 In _0.53 As / InP hetero system is
Compared to the nSb Hall element of about 2% / ° C, it is about one digit smaller.

In addition to Ga _0.47 In _0.53 As / InP heterojunction system, there is a heterojunction Hall element using Al _0.3 Ga _0.7 As / GaAs system (Taguchi Takashi et al., IEICE Transactions C, J70-C volume). , 5 (198
7), p. 758). Al _w Ga _1-w A with Al composition ratio _w
The band gap ((Eg) _w ) of s is given by the following equation (2). (Eg) _w = 1.424 + 1.247 · w (2) When w = 0.3, (Eg) _w is 1.80 eV. Ga
The band gap of As is 1.43 eV. Therefore, the difference in band gap between the two is 0.37 eV. Al _0.3
The absolute value of α of the Ga _0.7 As / GaAs heterojunction Hall element is 0.68% / ° C (Taguchi Takashi et al., IEICE Transactions C, J70-C, Vol. 5 (198).
7), p. 758).

Ga _0.2 In _0.8 As / Al _0.48 I
n _0.52 As heterojunction Hall element is also known (Y.S.
ugiyama, Technical Digest of the 11th Sensor Sympo
sium (1992), p. 79). The band gap of Ga _0.2 In _0.8 As at room temperature is 1.21 eV, and Al _0.48 In _0.52 As
Is 1.49 eV (HC Casey, Jr., and MBPa
nish, "HETERO STRUCTUR LASERS-Part B" (Academic Pre
ss (1978), p. 16). Therefore, the band gap difference is 0.28 eV. Ga _0.2 I in the case of voltage drive
The α of the n _0.8 As / Al _0.48 In _0.52 As heterojunction Hall element is reported to be 0.54% / ° C. (Y. Sugiyam
a, Technical Digest of the 11th Sensor Symposium (1
992), p. 79). The above-mentioned conventional Hall element composed of a heterojunction system has higher sensitivity than that of the GaAs Hall element, but α is larger.

A large α inevitably causes a large change in the Hall output voltage due to the operating environment temperature. Therefore, an auxiliary circuit that compensates for variations in output voltage due to temperature is required. This causes complication in the process, and if an auxiliary circuit is provided, the system including the Hall element is enlarged. To reduce α, a larger band gap difference than before,
Consequently, it is necessary to utilize a heterojunction system that results in a large conduction band discontinuity.

[0009]

In order to reduce α of the conventional heterojunction Hall element, it is necessary to form the heterojunction from semiconductors having a large band gap difference. Also,
In order to obtain high sensitivity characteristics, it is necessary to use a heterojunction system capable of expressing high electron mobility. However, a heterojunction system having a large bandgap difference suitable for a Hall element has not yet been proposed. This is one of the reasons why the temperature change of the Hall output voltage with high sensitivity prevents the realization of the heterojunction Hall element which is as small as the conventional GaAs Hall element. A high-performance heterojunction Hall element can be provided by newly discovering a heterojunction system that has high sensitivity characteristics and small temperature fluctuations in Hall output voltage.

[0010]

In the present invention, by forming a heterojunction with a semiconductor having a forbidden band width of 0.64 eV or more, it is possible to overcome the drawback of the conventional Hall output voltage having a large temperature change coefficient and to achieve high sensitivity. A hetero Hall element having a small Hall output voltage variation with temperature is obtained. FIG. 3 shows the results of the study by the inventor of the relationship between the band gap difference of the semiconductor material forming the heterojunction and the temperature coefficient of the Hall element. The temperature coefficient monotonically decreases with an increase in the band gap difference between the two semiconductors forming the heterojunction. It was found that when the band gap difference is less than 0.64 eV, it is difficult to obtain α of about 0.1% or less, which is considered to be practically suitable for the device. It was suggested that it is possible to obtain α smaller than 0.1% at 0.64 eV or more. Such a heterojunction is Ga _x In _1-x P or Al _z In _1-z.
It is achieved by joining P with Ga _y In _1-y As.

The band gaps ((Eg) _x , (Eg) _z ) of Ga _x In _1-x P and Al _z In _1-z P are obtained from equations (3) and (4), respectively. _{(Eg) x = 1.351 + 0.643} · x + 0.786 · X 2 ...... formula _{(3) (Eg) z =} 1.351 + 2.23 · z ...... formula (4) From the above equation x = 0.51 ± In the range of 0.02, (Eg) _x
Is 1.85 to 1.91 eV. z = 0.52 ± 0.0
In the range of 2, (Eg) _z is 2.47 to 2.56 eV. Band gap of Ga _y In _1-y As ((Eg)
_y ) is given by the following equation (5) as a function of the Ga composition ratio (y). (Eg) _y = 0.36 + 1.064 · y Equation (5) From Equation (5), for example, when y = 0.8, (Eg) _y is 1.2.
It will be 1 eV. Therefore, the band gap difference from Ga _0.8 In _0.2 As is x = 0.51 ± 0.02 Ga _x In
_It is 0.64 to 0.70 eV for _1- xP. on the other hand,
It is 1.26 to 1.35 eV for Al _z In _1-z P of z = 0.52 ± 0.02.

In the present invention, in order to obtain a high-performance heterojunction,
Ga _x I having a Ga composition ratio (x) of 0.49 or more and 0.53 or less
A heterojunction is formed from n _1-x P and Ga _y In _1-y As having a Ga composition ratio (y) of 0.10 or more and 0.40 or less. Alternatively, the Al composition ratio (z) is 0.50 or more and 0.54.
The following Al _z In _{1 -z} P and Ga composition ratio (y) are 0.10
A heterojunction is formed with Ga _y In _1-y As that is 0.40 or less. In either case, the Hall element is composed of a heterojunction system that gives a difference in forbidden band of 0.64 eV or more.

[0013] _{Ga x In 1-x P /} Ga y In 1-y As and _{Al z In 1-z P /} Ga y In 1-y As heterojunction deposited on the crystal substrate. G with a Ga composition ratio (x) of 0.51
a _0.51 In _0.49 P and Al 0.52 with Al composition ratio z _0.52
Since In _0.48 P lattice-matches with GaAs, it is convenient to use a semi-insulating GaAs single crystal as the substrate. Due to the characteristics of the Hall element, it is preferable to store x in the range of 0.51 ± 0.02. It is advisable to store z in the range of 0.52 ± 0.02. If x and z exceed this range, they may induce crystal defects in the Ga _y In _1-y As that makes these layers heterojunction. High electron mobility is not revealed in a heterojunction system containing a large amount of crystal defects. Therefore, a high-sensitivity heterojunction Hall element cannot be realized. This is because the sensitivity of the Hall element improves in proportion to the electron mobility of the base material.

Ga _x In _1-x P or Al _z In _1-z
The Ga composition ratio (y) of Ga _y In _1-y As to be heterojunction with P is preferably 0.30 to 0.40 or less. This is because the lattice mismatch with GaAs increases as y increases. As the lattice mismatch increases, Ga _y In _1-y As
Deteriorates the crystallinity of H.sub.2 and hinders high sensitivity of the Hall element. y is set to 0.10 to 0.40 at which crystallinity is not significantly deteriorated and high electron mobility is obtained.

The above heterojunction system is a group IV or group IV
N-type Ga _x In _1-x P doped with Group VI element and Ga _y undoped or doped with Group IV or Group VI element
It is composed of In _1-y As. Alternatively, n with silicon added
In the type Al _z In _1-z P and n-type doped with undoped or sulfur or silicon Ga _y In _1-y As constituting the heterojunction.

In constructing the heterojunction according to the present invention, n-type Ga _x In _1-x P doped with an element of group IV or group VI of the periodic table of elements and undoped or group IV or group VI A heterojunction is formed with Ga _y In _1-y As doped with the element. n-type Ga _x In _1-x P or Ga _y
Suitable Group IV or Group VI dopants for obtaining In _1-y As include Si, S, and Se. When n-type Ga _x In _1-x P is obtained by adding these dopants, a carrier concentration of 10 ¹⁷ to 10 ¹⁸ cm ^-3 is suitable for high mobility. The Ga _y In _1-y As for heterojunction with the n-type Ga _x In _1-x P is undoped or n-type doped with the above dopant. In order to obtain high mobility, the carrier concentration of Ga _y In _1-y As is 10
Around ¹⁶ cm ^-3 is suitable.

In order to obtain an n-type Al _z In _1-z P heterojunction with n-type Ga _y In _1-y As, Si is used as a dopant. N-type Ga _y In _1-y As was obtained by using a doping gas such as hydrogen sulfide (H ₂ S) containing S and Se of Group VI of the periodic table and hydrogen selenide (H ₂ Se). For example, trimethyl Al ((CH ₃ ) ₃ A
l) causes a gas phase reaction with an organic compound serving as an Al source,
It deteriorates the morphology of the crystal surface. N-type Si-doped Al _z In _1-z P and n-type is heterozygous Ga _y an In
_1-y As is an n-type layer undoped or doped with S or Si. Al _z In _1-z P forming a heterojunction
And Ga _y In _1-y As have carrier concentrations of 10 ¹⁷ to 10 ¹⁸
High mobilities can be obtained by setting cm ^-3 and 10 ¹⁶ cm ^-3 respectively.

Ga _x In _1-x P or Al _z In _1-z
There is no limitation on the stacking order of P and Ga _y In _1-y As.
However, when a single heterostructure is used, Ga is generally
_x In _1-x P or Al _z In _1-z P firstly on or GaAs buffer layer on the substrate, it is deposited. Ga _y In _1-y As having a small band gap is deposited on these mixed crystal layers. Ga _x I having a larger band gap than Ga _y In _1-y As
This is because if n _1-x P or Al _z In _1-z P is used as the outermost layer, it is difficult to impart ohmic properties to the input / output electrodes.

The heterojunction constituent layer such as Ga _y In _{1 -y} As is grown by a liquid phase epitaxial growth method (LPE method), a molecular beam epitaxial growth method (MBE method), a metal organic thermal decomposition method (MOVPE method), or the like. it can. Or MOV again
It can also be obtained by the MO / MBE method in which both PE and MBE are combined.

[0020]

When a Hall element is manufactured using a heterojunction material, a small temperature coefficient and high electron mobility are obtained by defining the bandgap of the material forming the heterojunction.

[0021]

EXAMPLES The present invention will be described in detail based on examples. FIG.
FIG. 3 is a schematic plan view of a Ga _x In _1-x As (x represents a Ga composition ratio) Hall element according to the present invention. 2 is a schematic cross-sectional view taken along the broken line AA ′ shown in FIG. In this example, a semi-insulating GaAs single crystal having a surface resistance of {100} and a specific resistance of about 10 ⁷ Ω · cm was used as a substrate (101).
Used as.

On the substrate (101), a high resistance undoped GaAs layer was deposited as a buffer layer (102). The thickness of the buffer layer (102) was about 100 nm.

On the buffer layer (102), S is used as a magnetic sensing layer.
i-doped n-type Al _0.52 In _0.48 P layer (103)
Was provided. Bandgap energy of the same layer is 2.51
It was eV, and as a result of measuring the carrier concentration by the Hall effect method, it was about 1 × 10 ¹⁸ cm ⁻³ . Monosilane gas (SiH ₄ ) was used for Si doping. The film thickness is 2
It was set to 5 nm.

On the Al _0.52 In _0.48 P layer (103),
Undoped n-type Ga _0.82 In _0.18 As magneto-sensitive layer (10
4) was deposited. The band gap energy of the same layer was 1.23 eV, the carrier concentration was 5 × 10 ¹⁶ cm ⁻³ , and the film thickness was 700 nm. As a result, n-type Al _0.52 In _0.48 P layer (103) and n-type Ga _0.82 I forming a heterojunction are formed.
The band gap energy difference from the n _0.18 As magnetosensitive layer (104) was 1.28 eV.

All the above semiconductor layers were grown by the MOVPE method under normal pressure. Cyclopentadienyl I as In source
n (C ₅ H ₅ In) was used. Trimethyl Ga and trimethyl Al were used as the raw materials of Ga and Al, respectively. As
Source, P source is arsine (AsH ₃ ), phosphine (PH
₃ ) and. The growth temperature was fixed at 660 ° C.

Next, the Ga _0.82 In _0.18 As magnetosensitive layer (10
The surface of 4) was covered with a normal organic photoresist material, and then the well-known photolithography technology and etching technology were used to process the regions where the input / output electrodes were to be formed and the regions to be the magnetic sensitive parts into mesa shapes. .

After that, the Ga _0.82 In _0.18 As magnetosensitive layer (1
The surface of 04) was coated again with the organic resist material.
Next, only the resist material existing in the formation regions of the pair of input electrodes (105) and output electrodes (106) is removed by using a known photolithography technique, respectively.
The surface of the a _0.82 In _0.18 As magnetosensitive layer (104) was exposed. Au / Ge containing about 13% by weight of Ge on it
The alloy was vacuum deposited. After the vapor deposition, the wafer was dipped in an organic solvent mixed solution, and the Au.Ge alloy film which was unnecessary for manufacturing the element was removed by a lift-off method using a resist material. next,
The wafer to which an alloy film to be an electrode was applied in order to obtain an ohmic electrode was heat-treated (alloyed) at a temperature of 420 ° C. for several minutes.

Further, a pad electrode (107) is provided on each electrode by being electrically connected to the input / output electrodes (105 and 106). The pad electrode (107) was placed on the surface layer of the GaAs single crystal substrate (101) exposed by mesa etching as described above. This is to prevent the magnetosensitive layer from being directly strained when the electrodes are alloyed.

The product sensitivity of the manufactured Hall element is 540 V /
AT, which is about 2 to 3 of the conventional GaAs Hall element.
Double product sensitivity was obtained. Further, α was 0.07% / ° C, which was smaller than that of the conventional heterojunction Hall element. This is shown as point A in FIG. This α was almost the same as that of conventional GaAs.

[0030]

The effect of the present invention is to improve the sensitivity of the heterojunction Hall element and suppress the temperature change of the characteristics to a low level.

[Brief description of drawings]

FIG. 1 is a schematic plan view of a Hall element according to the present invention.

FIG. 2 is a schematic diagram of a linear cross section taken along a broken line AA ′ in FIG.

FIG. 3 is a diagram showing a relationship between a band gap difference of a heterojunction and a temperature coefficient.

[Explanation of symbols]

(101) Substrate (102) Buffer layer (103) Al _0.52 In _0.48 P layer (104) Ga _0.82 In _0.18 As Magnetosensitive layer (105) Input electrode (106) Output electrode (107) Pad electrode (108) Oxide film ( 109) Dicing line

Claims (6)

[Claims] 1. A semiconductor crystal substrate having a bandgap difference of 0.
A Hall element comprising a heterojunction made of a semiconductor having a voltage of 64 eV or more. 2. The Ga composition ratio (x) of the heterojunction is 0.4.
9 above 0.53 following Ga _x In _1-x P and Ga composition ratio (y) is 0.10 to 0.40 Ga _y an In
The Hall element according to claim 1, which is composed of _1-yAs . 3. The Al composition ratio (z) of the heterojunction is 0.5.
Al _z In _1-z P of 0 or more and 0.54 or less and Ga _y In having a Ga composition ratio (y) of 0.10 or more and 0.40 or less
The Hall element according to claim 1, which is composed of _1-yAs . 4. An n-type Ga _x In _1-x P whose heterojunction is doped with an element of group IV or group VI of the periodic table and Ga _y which is undoped or doped with an element of group IV or group VI. 3. In _1-y As is included.
Hall element described in. 5. An n-type Al _z heterojunction doped with silicon
In _1-z P and the Hall element according to claim 3, characterized in that it comprises an undoped or sulfur or silicon-doped n-type Ga _y In _1-y As. 6. A Hall element comprising a heterojunction having an absolute value of the temperature coefficient of the Hall output voltage of 0.1% / ° C. or less.